1. Field of the Invention
The present invention relates to a watermark, and more particularly, to an apparatus for and method of embedding a watermark into original information, transmitting the watermarked information, and reconstructing the watermark.
2. Description of the Related Art
With the development of communications technologies based on networks, multimedia information is stored or transmitted more frequently in a digital form. When digital information is copied from original digital information, it is almost impossible to distinguish the copied digital information from the original digital information. Therefore, as a method to claim a right on the original information, identification information (hereinafter referred to as “a watermark”) is embedded in the original information. Copyright information of the original information, a signature of a copyright holder, or a mark is mainly used as the watermark.
If a size of data (watermark) embedded into the original information increases, the watermarked information becomes robust against external hacking attacks while a quality of the watermarked information is degraded. If the size of the data embedded into the original information decreases, the result is the opposite. That is, there is a trade-off between the size of the watermark and the quality of the watermarked information. When text data is embedded as the watermark, there is no problem in maintaining the quality of the watermark information since an amount of the text data is usually less than 100 bits. However, when image data is embedded as the watermark, for example, even a binary image of 32×32 pixels, which is relatively small compared to other image data, needs the embedding of 1024 bits, and therefore the quality of the original information is degraded. However, necessity for embedding a watermark image has increased because the image data is more discriminating and user-friendly displayable than the text data.
In the prior art, a variety of watermark embedding methods have been disclosed. However, all the methods are mainly about where and how watermarked data is embedded into the original information.